Willsenton R8 Revisited: ISO Output Transformer Finale
ฝัง
- เผยแพร่เมื่อ 8 ก.พ. 2025
- The final episode of my R8 saga! I go over the feedback tweak, an interesting bandwidth observation/test and finally my favorite tubes in the amp.
It's been a fun ride, we made some nice improvements but it's time to move on to something new!
You can buy the PSvane Horizon tubes here:
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You can find these transformers at Tubes USA:
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Thanks. Waiting for your own PP build. ISO is definitively on my list.
It really is a good investment.
This series has been a great journey to follow. You did a great job and went way above what most or all others would do. Thank you
Glad you enjoyed it!
That is a piece of art! Very NICE ! ! ! 😊
Dear and respected Steph, I have been following and enjoying your channel since I bought my first tube amp (Willsenton R8- 2021) and had a lot of fun tube rolling. Mainly NOS sylvanians, RFT, Melz, Psvane, Tung Sol..etc. Beautiful game and great variations of good sound, pure fun and enjoyment until after a year on Willsenton one channel died. But I managed to solve it just by thanking you. But let's get back to the topic. Yes, the Wilsenton R8 is a very good amplifier, but under the condition that those 5 levels of problems that you mentioned + transformers are corrected....so what remains good, only the chassis? And the most interesting thing lies in the fact that I bought it based on "reputable" American reviewers and reviews. The world shouldn't be all about ads, paid reviews, etc. and the money behind them. Thank you very much for your openness, sincerity, expertises and advices. Not everything that is cheap is good, but not everything that is expensive is good either. Good health and all the best in the New Year....D
And yes, I sold it. Just was affraid it'll burn my new Fyne audio speakers. Now happy as a young monkey !!! 😊😊
The transformers were an upgrade, the rest of the circuit + power transformer are there. The stock output transformers aren't "defective" like the R300, but aren't world class either.
Steph~ Great video in that, as in the case of Tube Amps,; And yes I'm talking Amps, Having a great transformer is key (Fact of Science and Subjective listening). Many tube amplifiers have a sound described as "warm," or "round". This sound can be very nice to listen to. However, it is the output transformers that produce the "warmth" or the tone of the sound, and it is actually a type of distortion, though pleasant (Tubes with Vinyl can be bliss). The detail of the music can be lost in the "warmth." There is no doubt that many people love the warmth of what they think is the tube, but is actually the transformer.
With the cap across the feedback resistor it’s very similar to a presence control on a guitar amp. The presence control is a var resistor in front of the cap to vary how much goes through. This really helps control the high end of an amp.
Nice ending of an interesting project ......ending with good common sense and experience .
Indeed intelligent use of tube rolling is key of finishing a tube based system .........don't take it on first degree when a tube rolls of te table ........yes it happens !
For the SS fans .......when a SS amplifier ( high quality ) goes bad on one channel and that amplifier is repaired , do NOT be surprised that one channel sounds tonaly different from the other channel .........when they did not used the same transistors/ comopnents for the repair.......in a heavy NFB type ampifeir this will not make huge dufference but those amps are not those renowed for their musicality anyway .
Thanks Steph you made it a great project for many tuby audiophiles ......
Indeed, if tube rolling is a thing, transistor rolling is definitely some sort of a thing as well. Only they physically and metaphorically don't roll very well and require a solder iron to do so. BTW, you don't even have to go so far up market for this to show. An entry level Sansui amp (meaning at the bottom of their own range) will already show the difference between transistors and coupling caps.
And being able to tube roll is one reason I limited the GNFB, add a lot and then all tubes sound very similar!
@@SkunkieDesignsElectronics YES
HI, I have the original R8 and was considering getting a quad matched set of the Horizon tubes from Amaz. but there unavailable , I was wondering where you got yours. This was a great re build video of the R8, even mine being the older version sounds better than a lot of other so called high end stuff out there, Thanks..
Hi. I'm really enjoying your videos and am impressed that Willsenton do appear to have recognised your contributions along with feedback from other modders. I would ask what you perceive to be the single most impactful mod that can be made to the R8. In a previous video you question the reasoning behind expensive tube rolling but not considering changing the 'iron'. So my layman's question is what makes the biggest difference and a supplementary question (for fun) is how does the modified amp sound with the original tubes that came with it? I realise that's very subjective and not 'measurable' in anything but qualitative terms but just curious. Thanks again for the videos. Best wishes
Best sonic mod is playing around with different tubes.
This morning, I replanced my pair of Amtrans AMRG 47k 3/4w carbon oxide loading resistors in my clone ANK L3 v2 phono stage (12AX7+6DJ8) to a pair of Charcroft Z-foil 0.4w. I expected to get more edgy sound but got the opposite. Z-foil gave me super micro detailed but more analog-like sound. They stay in my phono stage board. Don't get me wrong. The AMRG are really great but the Z-foil costs 4 times as much as the AMRG but the difference is only 26 USD a pair and you need only 1 pair for the loading resistor.
It would be interesting to see a mono block with those iso output transformers
HI, thank you for the whole R8 series. What is main (obvious) difference in sound quality after the iron upgrade? Regards.
Clarity and transparency in the top end, but mainly the bass response is on point!
I am so thankful that you have done a review on this brand of tubes . Also I would like to know your thoughts on Pure acoustics speakers I have bought a pair of them & at the price for 92db sensitivity 200 wattage speakers they are a bargain. Kindly check them out and do a review on them for your viewers
I'll check it out!
❤👍🎶 Greetings from Germany 🇩🇪
Hi Stephe, I think it would be a smart move of Willsenton if they would make a deal with you and pay you a (from their perspective) small fee and get an official endorsed Skunkie (limited) edition of their R8. They could put a little logo in the corner and sell all the mods straight out of the factory for a hefty premium. But I am just a YT watcher, heck I even mute the annoying commercials :)
They turned down my offer to be a consultant and my fee was only $5000. They actually turned around and threatened legal action in an "open letter" published on stereonet.com
I've been looking for output transformers like these, but there are issues with some of ISO output transformers. I build EL84/6V6GT push-pull amplifiers which require an 8k primary Z. The FC-25-8 is the closest match, but this model lacks screen grid taps. With this transformer, I might run my tubes in triode mode; not exactly what I need. The next option is to shell out almost $100 U.S. more for model FC-40-8, which comes with screen grid taps and is good to 40W, but is wasteful in terms of extra cost and power handling. TriodeUSA used to carry the excellent Dynaco replacement Z565 (wideband) transformers, but not anymore. I am still anxious to try out ISO transformers. But for you Stephe, I might not know about these.
The FC-25-8 has screen taps isotransformers.tokyo/push-pull-output-trans/fc-25-8%e8%8b%b1%e8%aa%9e/
Your ISO Tango frequency response curves are very similar to the specs of my 1970s Luxman pp amplifier - less than 1dB between 10-40,000Hz. I've seen frequency sweeps that prove it (trust but verify). I don't know why you'd want your hifi amp to be able to amplify radio signals but that was apparently a thing in the '70s!
I would not expect that audio amp operates at radio frequencies . First there is no enough RF signal to receive anything below 200kHz - one need long wire. Then who would believe that audio amplifier works above 200kHz? Me not.
Anyaway radio signals I sometime can spot also in my vintage tube tape recorder when is connected to my radio . According to me it must be SW range because any 1 m cable as areal can receive. but sure tape recorder not able to amplify SW waves . Such signals enter only amplifier and are detected stright at first tube then they may pass as audio 20 20kHz signal and be heard together with other sounds.
I do think the normal capacitance found in RCA cables might help limit SW/RF being picked up inadvertently.
Im not sure if this was covered, the 6sn7 on the rectifiler tube doesnt make a large difference which brand it is on a stock R8? Can we use different ones that postion? Can be costly to buy 4 matched quads when the amp might only need 2?
It can change the sound (And there is no rectifier tube) And no, it also doesn't always sound "best" to match it with the other pair of 6SN7 tubes.
@SkunkieDesignsElectronics thank you.
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Appreciate the detailed breakdown! I need some advice: My OKX wallet holds some USDT, and I have the seed phrase. (alarm fetch churn bridge exercise tape speak race clerk couch crater letter). How can I transfer them to Binance?
I see this bot comment on several channels.
Everything's probably unhooked by now, but if you're ever back to this amp again I wonder what your additional RC grid filter did to your square wave response. My money's on even less ringing that you already had gotten it down to? :)
I did test that and yes, a little bit less. The 10K was more rounded.
No thoughts about EL 34s in your tube rolling journey?
To me they defeat the purpose of buying a KT88 amp. Why buy a 45W amp KT88 UL amp in the first place if you only need 20-25W? Just get a EL34 amp like an ST70.
I personally think EL34 tubes just sound off in this amp that was voiced for UL/KT88 use. YMMV
Not really sure I know what I am talking about. Would it be possible to have variable negative feedback to give the amp a greater tubey sound ?
I've seen people install a multiple selection rotary switch to experiment with different amounts of feedback.
Maybe add a zobel to tame the overshoot and crazy high frequency range?
That's for someone smarter than me :)
So perhaps we might see Willsenton start to offer an R8 "premium" with a better set of output iron...
Forgive me if you already mentioned, but what speakers are you using with the R8?
I have some Fyne Audio F500 and a pair of Quad S2, small room.
hi,its a good job ,i would like to make a push-pull kt 88 so do you have any suggestions for a good shematic,thanks
I would start with one of the GEC schematics on the large data sheet. I can't imagine those don't work well.
gec ,you mean deneral electric company i suppose
@@SkunkieDesignsElectronics
tubedata.milbert.com/sheets/084/k/KT88_GEC.pdf
Hard to determine, can you possibly record some music from your speakers and post actual sound? Do you have a Tascam DR-07X or some such recorder? So we can actually hear something.
A) not risking copyright strike, I've seen a couple of folks banned for it B) EVERY DEMO sounds exactly the same once it is uploaded to YT and played on a computer. Not wasting my time, if that's a deal killed go watch those infomercials that say everything is great and play some fake music, that is probably the downloaded flac file laid over the video.
BTW do ANY of those other reviewers show you the transformer bandwidth or how to do anything other than spend your money on their affiliate links?
I never get people who think they can listen to a piece of audio on a recording, played back on an other piece of audio and get a true representation of what that sounds. To me that is the equivalence of a 3 star Michelin restaurant sending freeze dried samples of their restaurant offerings to potential customers. Sorry for sounding harsh about this, but this subject is kind of my battle horse :)
@@hugobloemers4425 I am also not big fan of such presentations because i have too good sound at my home and I am disappointed by 99% of real microphone snap shots in YT which are almost always done with lack of understanding.
BTW - you can spot my clips in my channel with such real recordings which were done 10 years ago with art least my minimum premeditation. These spakers I do not use any more - I've build according to me better ones but will not show them.
But I think about such presentations it is not as many people say . Experienced listener usualy has learned his system sounding and he then easy catches all unwelcomed inputs presented by such audio snap shots which are different from played direct from sources and abnormal differences which he knows are not generated by his home system. He can also deduct sounding of room acoustic where it is recorded. Anyway as I said it is never good enough to have value. for guiding
To me it's like trying to show a demo of color TV on a B&W television. The "sample" is gonna be dumbed down to the lowest quality or different parts in the chain. If you could make a cheapo "Chip amp" sound like a $10,000 tube amp just by listening to files recorded from a high end tube amp system, people would be doing that.
I understand people like the thought that they can sit on their couch, scroll through TH-cam and "audition" thousands of different systems without leaving their house. And people get a lot of views providing this phoney content, I'm not doing it.
I have decisions to make....
Tell George I sent you, he gives my viewers a small discount.
What are the OT specs for the Reisong A12?
cheap :P
🤤i need this amp … sell it to someone like … me 😍… fr